Redox Activation of Alkene Ligands in Platinum Complexes with Non-innocent Ligands

The reactivity of metal olefin complexes with non-innocent ligands (NILs) was examined. Treatment of PtCl2(diene) with the deprotonated catechol or aminophenol ligands afforded the corresponding Pt(NIL)(diene) complexes. The Pt( t BAFPh)(COD), Pt( t BAFPh)(nbd), and Pt(O2C6H2 t Bu2)(COD) (H2 t BAFPh = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, H2O2C6H2 t Bu2 = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt( t BAFPh)(COD) or Pt( t BAFPh)(nbd) with AgPF6 afforded the imino-semiquinones [Pt( t BAFPh)(COD)]PF6 or [Pt( t BAFPh)(nbd)]PF6, respectively. The [Pt( t BAFPh)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt( t BAFPh)(COD)]PF6, rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt( t BAFPh)(COD), [Pt( t BAFPh)(COD)]PF6, Pt( t BAFPh)(C8H12OMe), and [Cp2Co][Pt( t BAFPh)(C8H12OMe)] complexes were characterized crystallographically.